In normal-weight subjects, the effects of a high carbohydrate (hi-cho) vs high fat (hi-fat) diet/meal on lipoprotein lipase (lpl) responsiveness in adipose tissue (at) or skeletal muscle (sm)will predict weight stability vs weight gain over 5 yr and in obese subjects, the effects of a hi-cho vs hi-fat diet/meal on tissue-specific lpl responsiveness will predict weight stability of the obese weight vs additional weight gain over 5 yr.